The ultrasonic transducer instrument of this invention is preferably used in conjunction with a robotic transport device for positioning of the ultrasonic transducer instrument over a select well in the well plate for volume determination.
An ultrasonic transducer for volume determination is a sensor that can measure the distance to the surface level of the contents of a laboratory container without contact with the contents of the container. Knowing the distance to the bottom of an empty container, this sensor can therefore be used with a processor to determine the volume of the contents in a selected laboratory tube, open vial or other laboratory container, as well as a well in a well plate. Having the distance to the surface and the geometry and parameters of the container (and other numerous metrics indigenous to the material of the container and contents under examination) a programmed processor with the appropriate algorithm can calculate the volume of the contents in a target container.
The ultrasonic transducer as a volume sensor was devised to quickly determine the volume of the contents of a laboratory container by measuring the distance of a transducer emitter signal to the surface of the container contents, typically a liquid, using ultrasonic sound waves. The sound waves bounce off the surface of the container contents and return to a receiver for processing.
For containers having large diameter openings, a flat emitter element and a flat receiver element are sufficient. Combining the flat emitter element and the flat receiver element into a single transceiver element, which both emits and receives ultrasonic sound pulses, has enabled vessels with smaller diameter openings to be accessed with this technique of volume determination.
However, as the number of laboratory sample containers in a rack or plate increase, the density of container cells in a designated area also increases and therefore requires containers with very small openings. An ultrasonic transducer sensor with a flat transceiver element returns a weakly defined signal that cannot reliably be used to calculate the volume in wells in high-density well plates. Such well plates may include well arrays having 384 or 1536 wells. In such arrays, wells have an approximate well opening of 3 mm for the 384 well array, and 1.5 mm for the 1536 well array. As the target opening diminishes, the difficulty in focusing sound waves to the target opening increases.
Additional complexity is added by the fact well openings may be round or square, and may have acoustic effects inherent in the materials of the racks and well plates that dampen or reflect acoustic waves. The subject invention provides an instrument and a system to address these problems. The instrument by its basic tubular, shell-casing configuration is well adapted for mounting on laboratory robotic transport apparatus for access to select cells in arrays of segregated test samples.